Co-si based copper alloy plate

ABSTRACT

A Co—Si based copper alloy plate, comprising: Co: 0.5 to 3.0% by mass, Si: 0.1 to 1.0% by mass and the balance Cu with inevitable impurities, wherein the Co—Si based copper alloy plate satisfies the relationship {(60 degree specular gloss G(RD) in a rolling direction)−(60 degree specular gloss G(TD) in a direction transverse to rolling direction)}≧90%.

FIELD OF THE INVENTION

The present invention relates to a Co—Si based copper alloy plate.

DESCRIPTION OF THE RELATED ART

As small sized electric and electronic equipment such as a connector isneeded, a high strength Co—Si based copper alloy (Colson alloy) isdeveloped. Since the Co—Si based Colson alloy is provided by producing aprecipitate compound of Co and Si, it requires solution treatment athigh temperature and aging. Therefore, a firm oxide film is formed onthe surface, which degrades solder wettability. Also, the Colson alloymay be stress relief annealed after final roiling, which may furthergrow the oxide film. For this reason, acid pickling is conducted after afinal heat treatment, and the oxide film is dissolved and furtherremoved by buffing (hereinafter referred to as a “buffing with acidpickling”).

In view of the above, a copper alloy material having improved solderwettability by specifying surface roughness Ra of 0.2 μm or less and Rtof 2 μm or less (Patent Literature 1).

In addition, when the above-described buffing with acid pickling isconducted, ridged concave-convex is generated by buffing on the surface,thereby degrading the solder wettability. Therefore, a copper alloymaterial is developed by conducting acid pickling or degreasing beforefinish rolling, thereby improving the solder wettability (PatentLiterature 2). By conducting acid pickling or degreasing before finalrolling, a peak position in a frequency distribution graph representingconcave-convex components on the surface will appear at a plus side (ata convex component side) of a mean line for the roughness profile (0position in the frequency distribution graph), and solder wettabilityand plating property will be improved.

PRIOR ART DOCUMENTS Patent Literature

-   [Patent Literature 1] International Publication WO2010/013790-   [Patent Literature 2] Japanese Patent No. 4413992 (paragraph 0013)

Problems to be Solved by the Invention

However, in the case of the technology described in Patent Literature 1,even if the solder wettability is good, the oxide film on the surface ofthe material is not completely removed and acid pickling and grindingare conducted before the final rolling. Thus, once foreign matters arepushed by rolling, pin holes (partial areas where solder is notattached) may be generated. When the number of the pin holes increases,soldering may be imperfect. In particular, when the pin holes aregenerated at a soldered area where terminals are molded using the Colsonalloy, soldering may be imperfect.

In the case of the technology described in Patent Literature 2, acidpickling or degreasing is needed before the finish rolling, which makesthe process complicated and also makes productivity poor. In addition,the oxide film of the Co—Si based Colson alloy is quite firm, and istherefore not removed easily only by acid pickling. In the technologydescribed in Patent Literature 2, only acid pickling is conducted aftera heat treatment and no grinding is conducted, or no acid pickling andno grinding are conducted. It is considered that the oxide film on thesurface of the material is not completely removed, and the pin holes maybe easily generated.

Accordingly, the present invention is made to solve the above-describedproblems. An object thereof is to provide a Co—Si based copper alloyplate having excellent solder wettability and less pin holes generatedwhen soldering.

Means for Solving the Problems

Through intense studies by the present inventors, it is found that theexcellent solder wettability is attained and the number of the pin holesdecreases by conducting the buffing with acid pickling for a sufficientnumber of times using a relatively fine textured buff (grinding grains)after the final heat treatment such that the oxide film on the surfaceof the material and the foreign matters pushed by the rolling areremoved and a smooth surface having predetermined anisotropy isprovided.

In order to achieve the above-described object, the present inventionprovides a Co—Si based copper alloy plate, comprising: Co: 0.5 to 3.0%by mass, Si: 0.1 to 1.0% by mass and the balance Cu with inevitableimpurities, wherein the Co—Si based copper alloy plate satisfies therelationship {(60 degree specular gloss G(RD) in a rollingdirection)−(60 degree specular gloss G(TD) in a direction transverse torolling direction)}≧90%.

Preferably, a surface roughness Ra(RD) in a rolling direction is ≦0.07μm.

Preferably, a surface roughness Ra(RD) in a rolling direction is ≦0.50μm.

Preferably, a peak position in a frequency distribution graphrepresenting concave-convex components on a surface in the directiontransverse to rolling direction is at a minus side (a concave componentside) of a mean line for the roughness profile.

The Co—Si based copper alloy plate may further comprising a total of2.0% by mass or less of one or two or more selected from the groupconsisting of Mn, Fe, Mg, Ni, Cr, V, Nb, Mo, Zr, B, Ag, Be, Zn, Sn, amisch metal and P.

Effect of the Invention

According to the present invention, there can be provided a Co—Si basedcopper alloy plate having excellent solder wettability and less pinholes generated when soldering.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 A diagram showing an example of a production process of a Co—Sibased copper alloy plate according to an embodiment of the presentinvention.

FIG. 2 A frequency distribution graph of concave-convex components onthe surface in Example 4.

FIG. 3 A frequency distribution graph of concave-convex components onthe surface in Example 18.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, a Co—Si based copper alloy plate according to an embodimentof the present invention will be described. The symbol “%” herein refersto % by mass, unless otherwise specified.

In addition, the surface roughness Ra is arithmetic mean roughnessspecified in JIS-B0601 (2001), and the surface roughness Rz is a maximumheight roughness specified in the same JIS.

Referring to FIG. 1, a technical idea of the present invention will bedescribed. FIG. 1 shows an example of a production process of a Co—Sibased copper alloy plate according to the present invention.

First, when a copper alloy plate 2 after final heat treating is placedinto a pickling tank 4 and is acid pickled, an oxide film is dissolvedand thinned almost uniformly in a rolling direction (RD) and a directiontransverse to rolling direction (TD). Therefore, a 60 degree speculargloss G(RD) in a rolling direction and a 60 degree specular gloss G(TD)in a direction transverse to rolling direction are almost same afterpickling, and a difference {G(RD)−G(TD)} nearly equals to 0 (see FIG. 1(a)).

Next, a buff 6 is used to grind the copper alloy plate after acidpickling. Grinding mark flaws by buffing are left on a material. In therolling direction (RD) that is a rotation direction of the buff 6, asthe grinding on a surface of the material proceeds, the oxide film thatis not completely dissolved upon acid pickling disappears from thesurface of the material, the surface of the material becomes smooth andthe G(RD) becomes great. On the other hand, even if grinding of thesurface of the material proceeds in the direction transverse to rollingdirection (TD), the grinding mark flaws by buffing are formed on thesurface of the material in the TD direction. A degree of smooth is notlargely changed, and the G(RD) is not largely changed. It results in{G(RD)−G(TD)}>0. It is found that when {G(RD)−G(TD)}≧90%, the buffingproceeds to sufficiently remove the oxide film, improve the solderwettability and the pin holes generated when soldering are decreased. Anupper limit of {G(RD)−G(TD)} is not especially limited, but ispractically 400% or less.

The 60 degree specular gloss reflects a state of the surface of thematerial having a predetermined area. On the other hand, the surfaceroughness (such as Ra) reflects a state of the surface of the materialon a predetermined straight line. It is therefore considered that the 60degree specular gloss reflects the state of a locally existing oxidefilm and foreign matters on the surface of the material better than thesurface roughness.

The buff 6 is hollow cylindrical, and grinding grains are attached tothe surface thereof. By rotating the buff 6 in a forward direction,i.e., a threading direction of the copper alloy plate 2 (from left toright in FIG. 1), the grinding grains of the buff 6 grinds the surfaceof the copper alloy plate 2. Accordingly, a degree of the oxide filmremoval by the buffing process can be adjusted by a grain size (count)of respective grinding grains, a threading number of the copper alloyplate 2, a threading speed (line speed), a rotation number of the buff 6and the like.

Also, the surface roughness Ra (RD) in the rolling direction ispreferably 0.07 μm or less. If the Ra (RD) is less than 0.07 μm, thezero cross time may be decreased.

According to the present invention, a peak position in the frequencydistribution graph of concave-convex components on the surface in thedirection transverse to rolling direction can be specified. Here, thefrequency distribution graph of the concave-convex components on thesurface is identical with that described in Patent Literature 2, and isa plot where a horizontal axis represents a height from a mean line forthe roughness profile and a vertical axis represents a frequency(measurement data numbers). According to the present invention, thehorizontal axis is at 0.05 μm intervals (increments in between) for themean line for the roughness profile and the measurement data numbers atthe intervals are summed up as the frequency to generate the plot. The“mean line for the roughness profile” is specified in JIS-B0601.

Specifically, the frequency distribution graph is created as follows:(1) Firstly, “the height from a mean line for the roughness profile” ismeasured along a direction transverse to rolling direction of a sample.In other words, there are provided data of the height from the mean linefor the roughness profile (hereinafter referred to as “measurement data”as appropriate) per surface position. The peak position or the like isdetermined from the resultant measurement data, and the measurement datais numerically treated to calculate Ra and Rz. (2) The height from the“mean line for the roughness profile” is delimited at 0.05 μm intervals.(3) The measurement data numbers (frequency) are counted at the 0.05 μmintervals.

To provide the measurement data, measurement is made at an evaluationlength of 1.25 mm, a cut off value of 25 mm (in accordance withJIS-B0601) and a scan speed of 0.1 mm/sec. For the measurement, asurface roughness meter manufactured by Kosaka Laboratory Ltd.(Surfcorder SE3400) is used. The measurement data numbers are 7500points at an evaluation length of 1.25 mm.

Also, the method of measuring the peak position is identical with thatdescribed in Patent Literature 2. The resultant measurement data iscategorized as follows: When the height from “the mean line for theroughness profile” is more than 0, the data is categorized as upper(plus) components. When the height is less than 0, the data iscategorized as lower (minus) components. Thus, the frequencydistribution is plotted. The height (μm) from “the mean line for theroughness profile” is replotted on the horizontal axis. The measurementdata numbers are replotted as the frequency summed up at 0.05 μmintervals on the vertical axis. Thus, FIGS. 2 and 3 are provided(corresponding to FIG. 3 in Patent Literature 2). In FIGS. 2 and 3, atthe height from “the mean line for the roughness profile” of thehorizontal axis of 0 μm, a line is drawn to determined that the peakposition of the frequency is a concave component (at a minus side), aconvex component (at a plus side) or (0).

Here, the “peak position” is determined as follows: Firstly, from thegraphs (see FIGS. 2 and 3) of a height from “the mean line for afrequency-roughness curve”, the frequency having the highest value isdenoted as P1 and the frequency having the second highest value isdenoted as P2. (1) When P1 and P2 are in the minus side or whenP2/P1<99% and P1 is in the minus side, the peak position of thefrequency is a concave component (at a minus side). (2) When P1 and P2are in the plus side or when P2/P1<99% and P1 is in the plus side, thepeak position of the frequency is a convex component (at a plus side).(3) When P2/P1≧99% (except that both P1 and P2 are in the minus side andboth P1 and P2 are in the plus side), the peak position of the frequencyis 0.

Here, a line wherein the height from the mean line for the roughnessprofile being 0 μm is the mean line for the roughness profile.

When the peak positions measured three times may be in plus and minusand the peaks are in the upper (plus) components two times, they areconsidered as in the convex component side.

FIG. 2 is a graph replotted by the frequency (%) on the vertical axisand the height (μm) from the mean line for the roughness profile on thehorizontal axis about actual measurement data in Example 4 describedlater.

FIG. 3 is a graph replotted by the frequency (%) on the vertical axisand the height (μm) from the mean line for the roughness profile on thehorizontal axis about actual measurement data in Example 18 describedlater.

In FIG. 3, the peak position in the frequency distribution graph of theconcave-convex components on the surface is at the plus side (a convexcomponent side) of the mean line for the roughness profile. In FIG. 2,the peak position is at the minus side (a concave component side) of themean line for the roughness profile. In other words, according to thepresent invention (for example, FIG. 2 and Example 4), even when thepeak position is in the minus side (the concave component side), awetting property is good. The wetting property does not depend on thepeak position. In Example 18, the peak position is in the plus positionbecause an acid pickling solution is changed upon acid pickling.

The method of measuring the surface roughness Ra, Rz is identical withthat described in Patent Literature 2 and measurement is made at anevaluation length of 1.25 mm, a cut off value of 25 mm (in accordancewith JIS-B0601) and a scan speed of 0.1 mm/sec. For the measurement, asurface roughness meter manufactured by Kosaka Laboratory Ltd.(Surfcorder SE3400) is used. The measurement data numbers are 7500points at an evaluation length of 1.25 mm. The surface roughness Ra, Rzis measured three times, which are averaged.

Next, other definitions and compositions of the Co—Si based copper alloyplate according to the present invention will be described.

<Composition>

The composition includes Co: 0.5 to 3.0% by mass, Si: 0.1 to 1.0% bymass and the balance Cu with inevitable impurities. If the content of Coand Si is less than the above-defined range, precipitation by Co₂Si isinsufficient, and the strength cannot be enhanced. On the other hand, ifthe content of Co and Si exceeds the above-defined range, an electricalconductivity is degraded, and hot workability is also degraded. Thecontent of Co is preferably 1.5 to 2.5% by mass, more preferably 1.7 to2.2% by mass. The content of Si is preferably 0.3 to 0.7% by mass, morepreferably 0.4 to 0.55% by mass.

A mass ratio of Co/Si is preferably 3.5 to 5.0, more preferably 3.8 to4.6. Within the range of the mass ratio of Co/Si, Co₂Si can be fullyprecipitated.

Preferably, the composition further includes a total of 2.0% by mass orless of one or two or more selected from the group consisting of Mn, Mg,Ag, P, B, Zr, Fe, Ni, Cr, V, Nb, Mo, Be, Zn, Sn, and a misch metal. Ifthe total amount of the above element exceeds 2.0% by mass, thefollowing advantages are saturated and the productivity is degraded.However, if the total amount of the element is less than 0.001% by mass,fewer advantages are provided. The total amount of the element ispreferably 0.001 to 2.0% by mass, more preferably 0.01 to 2.0% by mass,most preferably 0.04 to 2.0% by mass.

Here, when a minor amount of Mn, Mg, Ag and P improves productproperties such as strength and a stress relaxation property withoutimpairing electric conductivity. The above-described advantage isprovided by dissolving the element mainly to a matrix in a solidsolution. When the element is contained in second phase particles,further advantages are provided.

Also, the addition of B, Zr and Fe improves the product properties suchas strength, electric conductivity, a stress relaxation property and aplating property. The above-described advantage is provided bydissolving the element mainly to a matrix in a solid solution. When theelement is contained in second phase particles, further advantages areprovided.

Ni, Cr, V, Nb, Mo, Be, Zn, Sn and a misch metal are complemented eachother, and improve not only strength and electric conductivity, but alsoproduction properties such as a stress relaxation property, bendingworkability, a plating property, and manufacturability such as a hotworkability by refining an ingot tissue.

In addition, elements that are not specifically described in the presentspecification may be added as long as the alloy of the present inventionis not adversely affected.

Next, an example of a method of producing the Co—Si based cooper alloyplate according to the present invention will be described. Firstly, aningot including copper, alloy element(s) required, and inevitableimpurities is hot rolled, mechanical finished, cold rolled, solutiontreated, and then aging treated to precipitate Co₂Si. Next, the materialis final cold rolled to have a predetermined thickness. If desired, astress relief annealing may be further conducted. Finally, the materialis acid pickled and is promptly buffing. Solution treatment may beconducted at any temperature within 700° C. to 1000° C. Aging treatmentmay be conducted at 400° C. to 650° C. for 1 to 20 hours. A reductionratio of the final cold rolling is preferably 5% to 50%, more preferably20% to 30%. A crystal grain size of the alloy material according to thepresent invention is not especially limited, but is generally 3 to 20μm. A grain size of the precipitate is 5 nm to 10 μm.

EXAMPLES

The ingot having the composition shown in Table 1 was casted, was hotrolled at 900° C. or more to have a thickness of 10 mm, mechanicalfinished to remove an oxidized scale on the surface, cold rolled,solution treated at a temperature within 700° C. to 1000° C., and thenaging treated at 400° C. to 650° C. for 1 to 20 hours. Next, thematerial was final cold rolled to have a predetermined thickness at areduction ratio of 5 to 40%. Further, the material was stress reliefannealed at 300 to 600° C. for 0.05 to 3 hours. Finally, the materialwas acid pickled and was promptly buffing under the conditions shown inTable 1. An acid pickling solution used for the acid pickling before thebuffing was a solution of dilute sulfuric acid, hydrochloric acid ordilute nitric acid at a concentration of 20 to 30% by mass at pH=1 orless. An immersion time in the acid pickling was 60 to 180 seconds. Abuffing material used for the buffing was alumina grinding grains, and anylon non-woven cloth containing the alumina. Buff materials havingdifferent buff texture roughnesses (counts of grinding grains) wereused. The count of the grinding grains represents the grinding grains bythe number of mesh per inch, and is specified by JIS R6001. For example,when the count is 1000, an average size of the grinding grains will be18 to 14.5 μm. Example 18 is similar to other Examples except that anitric acid solution at a concentration of 40 to 50% by mass at pH=1 orless was used as the acid pickling solution of the acid picklingbuffing.

Respective samples thus obtained were evaluated for a variety ofproperties.

(1) Ra and Rz

Arithmetic mean roughness Ra and a maximum height roughness Rz weremeasured in accordance with JIS B0601 (2001). Measurement was made inthe rolling direction (RD) and the direction transverse to rollingdirection (TD). The measurement was made at an evaluation length of 1.25mm, a cut off value of 0.25 mm (in accordance with the JIS abovedescribed) and a scan speed of 0.1 mm/sec. A surface roughness metermanufactured by Kosaka Laboratory Ltd. (Surfcorder SE3400) was used. Themeasurement data numbers are 7500 points at an evaluation length of 1.25mm.

(2) Frequency Distribution Graph

The measurement data in the direction transverse to rolling directionobtained in (1) was categorized into upper (plus) components and lower(minus) components from “the mean line for the roughness profile”, afrequency distribution was plotted by delimiting the height from the“mean line for the roughness profile” at 0.05 μm intervals. From themeasurement data, the frequency (%) was re-plotted on the vertical axis,and the height (μm) from “the mean line for the roughness profile” wasreplotted on the horizontal axis. Thus, FIGS. 2 and 3 were provided. InFIGS. 2 and 3, at the height from “the mean line for the roughnessprofile” of the horizontal axis of 0 μm, a line was drawn to determinethat the peak position of the frequency is a concave component (at aminus side), a convex component (at a plus side) or (0).

(3) Gloss

60 degree specular gloss was measured by using a gloss meter inaccordance with JIS-Z8741 (trade name “PG-1M” manufactured by NipponDenshoku Industries Co., Ltd.) at an entry angle of 60 degrees in therolling direction RD and the direction transverse to rolling directionTD.

FIG. 2 is a graph replotted by the frequency (%) on the vertical axisand the height (μm) from the mean line for the roughness profile on thehorizontal axis about actual measurement data in Example 4.

FIG. 3 is a graph replotted by the frequency (%) on the vertical axisand the height (μm) from the mean line for the roughness profile on thehorizontal axis about actual measurement data in Example 18 describedlater.

(3) Solder Properties (3-1) Pin Hole Number

A pin hole number refers to the number of the holes through which a basematerial (copper alloy material) is viewed without solder wetting. Whenthe pin hole number increases, soldering may be imperfect. The pin holenumber was tested by acid pickling each sample having a width of 10 mmwith a solution including 10% by mass of dilute sulfuric acid, immersingthe sample into a solder bath at an immersion depth of 12 mm, animmersion speed of 25 mm/s and an immersion time of 10 sec, and puffingup the sample from the solder bath. Front and back sides of the samplewere observed by an optical microscope (50 magnification), and thenumber of the pin holes through which the base material was visible wascounted. If the number was not more than 5, the sample was determined asgood.

A solder test was conducted in accordance with JIS-C60068-2-54. Thesolder bath composition was 60 wt % of tin and 40 wt % of lead. Anappropriate amount of a flux (25 wt % of rosin and 75 wt % of ethanol)was added thereto. A solder temperature was 235±3° C.

(3-1) Zero Cross Time (T2 Value)

A zero cross time (T2 value) refers to a time until a wet stress valuebecomes zero. The shorter the zero cross time is, the more the solderwets. The test was conducted by acid pickling the sample with a solutionincluding 10% by mass of dilute sulfuric acid, and immersing the sampleinto the above-described solder bath at an immersion depth of 4 mm, animmersion speed of 25 mm/s, an immersion time of 10 sec and 235±3° C. inaccordance with JIS-C60068-2-54. The zero cross time was determined by ameniscograph method. When the zero cross time was 2.0 sec or less, thesolder wettability was determined as good.

Tables 1 to 3 show the results obtained. As to “pretreatment beforefinish rolling” in Tables 1 and 2, methods A and B refer the buffingwith acid pickling under the conditions described below. For example, inExample 9, the buffing with add pickling was conducted before and afterthe finish rolling. The acid pickling solution used for the buffing withacid pickling before the finish rolling was same as the acid picklingsolution used for the buffing with acid pickling after the finishrolling discussed above.

Method A: Number of buffing time of 1, threading speed of 40 m/min, bufftexture roughnesses (grinding grains) of 1000 counts, and buff rotatingnumber of 500 rpm

Method B: Number of buffing time of 3, threading speed of 10 m/min, bufftexture roughnesses (grinding grains) of 2000 counts, and buff rotatingnumber of 1400 rpm

Some samples were only acid pickled with a 10% sulfuric acid solutionfor 30 sec before the finish rolling. Some samples were only degreasedby immersing into hexane for 30 sec before the finish rolling. The othersamples were not treated before the finish rolling.

TABLE 1 Buffing Production process Buff Pretreatment Stress Threadingtexture Rotation Composition (wt %) before Finish relief Acid Threadingspeed roughness number No. Co Si Other component finish rolling rollingannealing pickling Buffing number (m/min) (counts) (/min) Example 1 0.500.11 — — ◯ ◯ ◯ ◯ 3 10 2000 1400 Example 2 1.00 0.23 — — ◯ ◯ ◯ ◯ 3 102000 1400 Example 3 1.50 0.40 — — ◯ ◯ ◯ ◯ 3 10 2000 1400 Example 4 1.800.41 — — ◯ ◯ ◯ ◯ 3 10 2000 1400 Example 5 2.50 0.70 — — ◯ ◯ ◯ ◯ 3 102000 1400 Example 6 3.00 1.00 — — ◯ ◯ ◯ ◯ 3 10 2000 1400 Example 7 1.500.40 — — ◯ ◯ ◯ ◯ 2 10 2000 1400 Example 8 1.50 0.40 — — ◯ ◯ ◯ ◯ 4 104000 1400 Example 9 1.50 0.40 — Method A ◯ ◯ ◯ ◯ 3 10 2000 1400 Example10 1.50 0.40 — Method B ◯ ◯ ◯ ◯ 3 10 2000 1400 Example 11 1.50 0.40 —Only acid ◯ ◯ ◯ ◯ 3 10 2000 1400 pickling Example 12 1.50 0.40 — Only ◯◯ ◯ ◯ 3 10 2000 1400 degreasing Example 13 1.50 0.40 — — ◯ ◯ ◯ ◯ 2 102000 1200 Example 14 1.50 0.40 Mn: 0.1, Fe: 0.2, — ◯ ◯ ◯ ◯ 3 10 20001400 Mg: 0.05, Ni: 1.2 Example 15 1.50 0.40 Cr: 0.1, V: 0.2, — ◯ ◯ ◯ ◯ 310 2000 1400 Nb: 0.1, Mo: 0.1, Zr: 0.1 Example 16 1.50 0.40 B: 0.05, Ag:0.1, — ◯ ◯ ◯ ◯ 3 10 2000 1400 Zn: 0.5, Sn: 0.4 Example 17 1.50 0.40 Be:0.1, misch — ◯ ◯ ◯ ◯ 3 10 2000 1400 metal: 0.1, P0.05 Example 18 1.500.40 — — ◯ ◯ ◯ ◯ 3 10 2000 1400 Example 19 1.50 0.40 — — ◯ ◯ ◯ ◯ 6 104000 1500

TABLE 2 Buffing Composition (wt %) Production process Buff OtherPretreatment Stress Thread- Threading texture Rotation com- beforeFinish relief Acid ing speed roughness number No. Co Si ponent finishrolling rolling annealing pickling Buffing number (m/min) (counts)(/min) Comparative Example 1 1.50 0.40 — — ◯ ◯ ◯ ◯ 3 60 2000 1400Comparative Example 2 1.50 0.40 — — ◯ ◯ ◯ ◯ 3 100  2000 1400 ComparativeExample 3 1.50 0.40 — — ◯ ◯ ◯ ◯ 1 10 2000 1400 Comparative Example 41.50 0.40 — — ◯ — — — — — — — Comparative Example 5 1.50 0.40 — — ◯ ◯ ◯◯ 1 10 4000 1400 Comparative Example 6 1.50 0.40 — — ◯ ◯ ◯ ◯ 2 10 40001400 Comparative Example 7 1.50 0.40 — — ◯ ◯ ◯ ◯ 3 10 4000 1400Comparative Example 8 1.50 0.40 — — ◯ ◯ ◯ ◯ 1 10 500 1400 ComparativeExample 9 1.50 0.40 — — ◯ ◯ ◯ ◯ 2 10 500 1400 Comparative Example 101.50 0.40 — — ◯ ◯ ◯ ◯ 3 10 500 1400 Comparative Example 11 1.50 0.40 — —◯ ◯ ◯ ◯ 3 10 2000 200 Comparative Example 12 1.50 0.40 — — ◯ ◯ ◯ ◯ 3 102000 500 Comparative Example 13 1.50 0.40 — — ◯ ◯ ◯ — 1 10 — —Comparative Example 14 1.50 0.40 — Method A ◯ — — — — — — — ComparativeExample 15 1.50 0.40 — Method A ◯ ◯ ◯ ◯ 1 60 2000 500 ComparativeExample 16 1.50 0.40 — Only ◯ — — — — — — — degreasing ComparativeExample 17 1.50 0.40 — Only ◯ ◯ ◯ ◯ 1 60 2000 500 degreasing ComparativeExample 18 1.50 0.40 — Only acid ◯ — — — — — — — pickling ComparativeExample 19 1.50 0.40 — Only acid ◯ ◯ ◯ ◯ 1 60 2000 500 picklingComparative Example 20 1.50 0.40 — — ◯ ◯ ◯ ◯ 1 40 1000 500 ComparativeExample 21 1.50 0.40 — — ◯ — — — — — — —

TABLE 3 Solder Frequency properties distribution Zero curve Gloss G(60°) cross peak Ra (μm) Rz (μm) G(RD) − Pinhole time No. position RD TDRD TD RD TD G(TD) numbers (sec) Example 1 − 0.05 0.08 0.42 0.6 299 191108 0 1.61 Example 2 − 0.06 0.08 0.44 0.68 288 193 95 0 1.73 Example 3 −0.05 0.08 0.43 0.65 288 192 96 0 1.65 Example 4 − 0.06 0.08 0.43 0.67288 190 98 0 1.73 Example 5 − 0.05 0.08 0.44 0.66 293 192 101 0 1.62Example 6 − 0.06 0.08 0.43 0.68 288 192 96 0 1.81 Example 7 − 0.06 0.080.54 0.71 288 193 95 4 1.87 Example 8 − 0.04 0.06 0.35 0.53 387 288 99 01.59 Example 9 − 0.06 0.08 0.42 0.68 288 189 99 1 1.72 Example 10 − 0.050.08 0.43 0.68 297 190 107 0 1.65 Example 11 − 0.06 0.08 0.42 0.68 287190 97 1 1.82 Example 12 − 0.06 0.08 0.43 0.68 288 193 95 1 1.73 Example13 − 0.08 0.10 0.52 0.68 274 174 100 4 1.87 Example 14 − 0.06 0.08 0.420.66 288 186 102 0 1.70 Example 15 − 0.05 0.08 0.43 0.67 294 188 106 01.61 Example 16 − 0.06 0.08 0.42 0.66 288 188 100 0 1.70 Example 17 −0.06 0.09 0.43 0.67 288 179 109 0 1.71 Example 18 + 0.07 0.1 0.45 0.69276 168 108 3 1.59 Example 19 − 0.04 0.06 0.23 0.37 384 280 104 0 1.20Comparative Example 1 − 0.10 0.10 0.72 0.72 184 184 0 7 1.73 ComparativeExample 2 − 0.13 0.14 0.76 0.78 180 168 12 8 1.88 Comparative Example 3− 0.10 0.09 0.71 0.70 186 168 18 7 1.80 Comparative Example 4 − 0.310.28 1.54 1.74 123 134 −11 42 2.81 Comparative Example 5 − 0.14 0.150.82 0.83 160 153 7 13 1.88 Comparative Example 6 − 0.10 0.12 0.69 0.73175 170 5 9 1.87 Comparative Example 7 − 0.07 0.08 0.49 0.60 275 190 856 1.80 Comparative Example 8 − 0.34 0.38 2.38 2.42 120 100 20 11 2.64Comparative Example 9 − 0.35 0.38 2.45 2.42 122 102 20 12 2.48Comparative Example 10 − 0.34 0.38 2.38 2.48 121 100 21 11 2.43Comparative Example 11 − 0.13 0.13 0.78 0.79 174 158 16 9 1.84Comparative Example 12 − 0.10 0.11 0.68 0.71 184 175 9 6 1.87Comparative Example 13 − 0.15 0.15 0.82 0.83 151 158 −7 21 2.50Comparative Example 14 − 0.30 0.27 1.51 1.74 133 138 −5 20 1.87Comparative Example 15 − 0.12 0.13 1.42 1.43 169 160 9 8 1.85Comparative Example 16 + 0.30 0.28 1.52 1.86 130 145 −15 39 2.80Comparative Example 17 − 0.13 0.13 1.42 1.42 155 155 0 12 1.85Comparative Example 18 + 0.31 0.28 1.51 1.78 128 133 −5 28 2.45Comparative Example 19 − 0.12 0.13 1.42 1.43 175 178 −3 10 1.87Comparative Example 20 − 0.14 0.16 1.01 1.12 150 149 1 9 2.23Comparative Example 21 − 0.06 0.05 0.4 0.37 261 280 −19 38 2.73

As apparent from Tables 1 to 3, in each of Examples where the buffingwith acid pickling was conducted for a sufficient number of times usinga relatively fine textured buff (grinding grains) after a final heattreatment (stress relief annealed), the solder wettability wasexcellent, and the pin holes are decreased. In each Example, {(60 degreespecular gloss G(RD) in a rolling direction)−(60 degree specular glossG(TD) in a direction transverse to rolling direction)}≧90%. It isconsidered that the oxide film on the surface of the material and theforeign matters pushed are sufficiently removed and the surface becomessmooth.

The buffing with acid pickling in each Example was conducted under theconditions: grinding grains of 2000 counts or more, threading time oftwo or more, threading speed of 10 mpm or less, and rotating number of1200 rpm or more. It should be appreciated that these optimum ranges arechanged depending on a production apparatus.

On the other hand, in each of Comparative Examples where the buffingwith acid pickling was conducted insufficiently, the oxide film on thesurface of the material and the foreign matters pushed are notsufficiently removed. Therefore, in each Comparative Example, {(60degree specular gloss G(RD) in a rolling direction)−(60 degree speculargloss G(TD) in a direction transverse to rolling direction)}<90%. Thepin holes are increased, and the solder wettability was degraded whenthe oxide film was remained largely.

A cause of degradation may be that when the buffing with acid picklingwas conducted in Comparative Examples 1, 2, 15, 17 and 19, the threadingspeed exceeded 20 mpm.

The cause of degradation may be that in Comparative Examples 3, 5, 8 and20 the threading time was less than two. Notably, in Comparative Example20, the buffing with acid pickling was conducted using theabove-described method A after the final rolling.

The cause of degradation may be that in Comparative Example 13 nobuffing was conducted although acid pickling was conducted.

In Comparative Examples 6 and 7 where the count of the grinding grainsused in the buffing with acid pickling was 4000, the grinding grainswere too fine to grind, and it is thus considered that Ra(RD) is not sodecreased.

The cause of degradation may be that, in Comparative Examples 11 and 12,the rotating number in the buffing with acid pickling was less than 1200rpm.

In Comparative Examples 9 and 10, the grinding grains were coarse andthe surface after the buffing with add pickling became roughened, {(60degree specular gloss G(RD) in a rolling direction)−(60 degree speculargloss G(TD) in a direction transverse to rolling direction)}<90%, thepin holes are increased and the zero cross time was bad. It isconsidered that, since the count of the grinding grains used in thebuffing with acid pickling was 500, the grinding grains were too coarse.

The cause of degradation may be that, in Comparative Examples 4, 14, 16,18 and 21 where no buffing with acid pickling was conducted after thefinal roiling, the oxide film on the surface and the foreign matterspushed were not removed and the rolled surface was left as it is.Comparative Example 21 was similar to each Example except that theroughness of the mill rolls of the final rolling was finer.

In Comparative Examples 16 and 18, the treatment (acid pickling ordegreasing) was conducted before the finish rolling and no buffing withacid pickling was conducted. As a result, the peak position was at theplus side (at the convex component side) of the mean line for theroughness profile (0 position in the frequency distribution graphrepresenting the concave-convex components on the surface). In otherwords, these Comparative Examples show the copper alloy plate describedin Patent Literature 2.

In Comparative Examples 4, 13, 16 and 21, the zero cross time exceeded2M sec and the solder wettability was degraded, It is considered that,since no acid pickling and no buffing were conducted, the oxide filmremained on the surface of the metal (Comparative Example 16 correspondsto the conditions described in Patent Literature 2).

1. A Co—Si based copper alloy plate, comprising: Co: 0.5 to 3.0% bymass, Si: 0.1 to 1.0% by mass and the balance Cu with inevitableimpurities, wherein the Co—Si based copper alloy plate satisfies therelationship {(60 degree specular gloss G(RD) in a rollingdirection)−(60 degree specular gloss G(TD) in a direction transverse torolling direction)}≧90%.
 2. The Co—Si based copper alloy plate accordingto claim 1, wherein a surface roughness Ra(RD) in a rolling direction is≦0.07 μm.
 3. The Co—Si based copper alloy plate according to claim 2,wherein a surface roughness Ra(RD) in a rolling direction is ≦0.50 μm.4. The Co—Si based copper alloy plate according to claim 1, wherein apeak position in a frequency distribution graph representingconcave-convex components on a surface in the direction transverse torolling direction is at a minus side (a concave component side) of amean line for the roughness profile.
 5. The Co—Si based copper alloyplate according to claim 1, further comprising a total of 2.0% by massor less of one or two or more selected from the group consisting of Mn,Fe, Mg, Ni, Cr, V, Nb, Mo, Zr, B, Ag, Be, Zn, Sn, a misch metal and P.